1. Field of the Invention
This invention relates to a process and apparatus for recovery of the energy values of waste tar materials by injecting such materials into a coke oven. More particularly, the invention provides a process of injecting into a coke oven waste tar sludge containing volatile hydrocarbons, such as benzene, while minimizing release of such hydrocarbons into the atmosphere.
2. Related Prior Art
It has been known to use waste tar products as additives to a coke oven charge by grinding the waste tar products, adding a diluent, and spraying the diluted tar onto coking coal before charging into the coke ovens. Such prior art processes have the disadvantage of releasing volatiles, such as benzene, contained in the tar, into the open atmosphere, with attendant environmental problems.
Early prior art may have involved adding coal tar pitch, without coal, to a coke oven. Such process did not produce coke.
U.S. Pat. No. 3,146,183 to Reed et al. describes a process of premixing tar sludge and coal for charging into a coke oven. According to this patent, it is unsatisfactory to add tar decanter sludge directly to the coal after or while it is being deposited in the coke oven. If the sludge is added at the top of the bed after the entire charge (of coal) is added to the coke oven, most of the sludge is near the top of the oven and, as the heating of the coal charge is effected during the coking operation, part of the sludge is evaporated and swept out by the hot gases emanating from the coking coal. Furthermore, the sludge is unevenly distributed over the coal and effective coking is not accomphished. According to this patent, addition of the sludge during the charging of the coke oven with coal interferes with the charging operation and the longer time required for such charging operation reduces the production capacity of a coke oven.